Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <bits/stdc++.h>

using namespace std;

const vector<int> dx = {1, -1, 0, 0}, dy = {0, 0, 1, -1};

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int H, W;
  cin >> H >> W;
  int cnt = 0;
  vector<string> S(H);
  for (int i = 0; i < H; i++) {
    cin >> S[i];
    for (int j = 0; j < W; j++) {
      if (S[i][j] == '#') cnt++;
    }
  }
  vector<vector<int>> D(H, vector<int>(W, -1));
  D[0][0] = 1;
  queue<pair<int, int>> que;
  que.push(make_pair(0, 0));
  while (!que.empty()) {
    auto q = que.front();
    que.pop();
    int y = q.first, x = q.second;
    for (int i = 0; i < 4; i++) {
      int ny = y + dy[i], nx = x + dx[i];
      if (ny < 0 || ny >= H || nx < 0 || nx >= W) continue;
      if (D[ny][nx] != -1 || S[ny][nx] == '#') continue;
      D[ny][nx] = D[y][x] + 1;
      que.push(make_pair(ny, nx));
    }
  }
  cout << (D[H - 1][W - 1] == -1 ? -1 : H * W - cnt - D[H - 1][W - 1]) << '\n';
  return 0;
}